Multimedia streams, which typically include video frames, are compressed prior to transmission or storage, to conserve bandwidth. Compressing video generally means representing a relatively larger group of bits with a relatively smaller group of bits. Received compressed multimedia streams are decompressed back to their (approximate) original format for display.
It will readily be appreciated that many compression schemes are possible. More specifically, many different compression schemes, which use algorithms and/or basis functions (collectively herein, “compression algorithms”), are possible. Ordinarily two goals exist for compression. One, of course, is to compress the multimedia stream as much as possible. Competing with the first goal is the desire not to lose excessive information during the compression and expansion process. A high quality encoder, which is the name of the device typically used for compression, is configured with fixed compression algorithms that seek to optimize these two competing goals.
The present invention recognizes that depending on the nature of the particular multimedia streams to be compressed, a first compression scheme might be optimal for a first stream while a second compression scheme might be optimal for a second stream. Indeed, the compression of different parts of the same stream might be best optimized using more than a single compression scheme.
One way to handle this would be to provide an encoder that could dynamically change its compression algorithms to suit the multimedia stream currently being compressed. As understood by the present invention, however, this could require changing the compression algorithm, measuring the quality of the resulting compression, changing the algorithm again, and so on, with the candidate algorithms being tested in series. As further understood herein, while this might be acceptable for storing compressed streams, it is problematic in the context of transmission of compressed multimedia, during which sufficient time might not exist to test candidate compression algorithms in series. Having made these critical observations, the invention disclosed below has been provided.